The Megaflora from the Quantico Locality (Upper Albian), Lower Cretaceous Potomac Group of Virginia

Abstract

The megaflora documented in this paper from Quantico, Virginia, is one of the first assemblages of Lower Cretaceous angiosperm megafossils from North America to be described in detail using modem methods of foliar architectural analysis. The megaflora is of middle to early late Albian age and consists of 22 species of leaves/shoots and at least 5 species of reproductive structures. Three new species are described in this publication. Estimates of botanical diversity indicate the presence of at least 1 species of pteridophyte (Equisetum), 1 species of cycadophyte, 9 species of conifers, and 12 species of angiosperms (all dicotyledons). A minimum of 5 angiosperm species are referable to the dicot subclass Magnoliidae, including leaves with affinities to extant Laurales, and leaves and associated reproductive structures with affinities to extant Nelumbonaceae (placed in Ranunculidae by some authors). Also present are leaf megafossils with probable affinities to the dicot subclasses Rosidae and/or Hamamelididae (2 species of Sapindopsis), other possible Hamamelididae (1 species of "platanoid" leaf fragments), and specimens assigned to the form genus Dicotylophylum. Evidence from sedimentology, megafossil preservation, and the morphology of the most abundant species (Nelumbites exmuinervis) indicates that the fossil-bearing beds at Quantico probably represent deposition in a pond or swale. The megaflora consists of both herbaceous aquatic angiosperms representing in situ elements and remains of woody gymnosperms and angiosperms transported from nearby terrestrial environments.